Seasonal and site-specific variability in terrigenous particulate organic carbon concentration in near-shore waters of Lake Biwa, Japan

Identifying sources of particulate organic matter (POM) is important for clarifying fundamental mechanisms by which lake food webs are sustained. We determined carbon and nitrogen stable isotope ratios of POM in near-shore waters of Lake Biwa, a large, meso-eutrophic lake in Japan, to estimate relative contributions of terrigenous particulate organic carbon (T-POC), plankton-derived POC (P-POC) and epilithon-derived POC (E-POC) to POC in near-shore waters. Samples were collected during different months (November, February, May and July) at 29 sites located near the mouth of tributary rivers with different discharge and catchment land use. The data revealed that POC mainly consisted of P-POC and T-POC, with relative contributions varying widely over season and among locations. E-POC generally contributed little to the near-shore POC. Path analyses revealed that the concentration of riverine POC whose isotopic signatures were similar to those of rice straws increased with a larger %paddy field area in the catchment of tributary rivers, which subsequently enhanced T-POC inputs to near-shore waters through riverine transportation. Furthermore, our results suggested that T-POC contribution was influenced, with a time lag, by wave-driven turbulence and shore topography, which appear to affect sedimentation and resuspension of T-POC

Is the Relationship between Body Size and Trophic Niche Position Time-Invariant in a Predatory Fish? First Stable Isotope Evidence

Characterizing relationships between individual body size and trophic niche position is essential for understanding how population and food-web dynamics are mediated by size-dependent trophic interactions. However, whether (and how) intraspecific size-trophic relationships (i.e., trophic ontogeny pattern at the population level) vary with time remains poorly understood. Using archival specimens of a freshwater predatory fish Gymnogobius isaza (Tanaka 1916) from Lake Biwa, Japan, we assembled a long-term (>40 years) time-series of the size-dependence of trophic niche position by examining nitrogen stable isotope ratios (δ15N) of the fish specimens. The size-dependence of trophic niche position was defined as the slope of the relationship between δ15N and log body size. Our analyses showed that the slope was significantly positive in about 60% of years and null in other years, changing through time. This is the first quantitative (i.e., stable isotope) evidence of long-term variability in the size-trophic relationship in a predatory fish. This finding had implications for the fish trophic dynamics, despite that about 60% of the yearly values were not statistically different from the long-term average. We proposed hypotheses for the underlying mechanism of the time-varying size-trophic relationship

Utility of Nd isotope ratio as a tracer of marine animals : regional variation in coastal seas and causal factors

Isotopic compositions of animal tissue are an intrinsic marker commonly used to trace animal origins and migrations; however, few isotopes are effective for this purpose in marine environments, especially on a local scale. The isotope ratio of the lanthanoid element neodymium (Nd) is a promising tracer for coastal animal migrations. Neodymium derives from the same geologic materials as strontium, well known as an isotopic tracer (87Sr/86Sr) for terrestrial and anadromous animals. The advantage of the Nd isotope ratio (143Nd/144Nd, expressed as εNd) is that it varies greatly in the ocean according to the geology of the neighboring continents, whereas oceanic 87Sr/86Sr is highly uniform. This study explored the utility of the Nd isotope ratio as a marine tracer by investigating the variation of εNd preserved in tissues of coastal species, and the causes of that variation, in a region of northeastern Japan where the bedrock geology is highly variable. We measured εNd and 87Sr/86Sr in seawater, river water, and soft tissues of sedentary suspension feeders: the mussels Mytilus galloprovincialis and Mytilus coruscus and the oyster Crassostrea gigas. We also measured concentrations of three lanthanoids (La, Ce, and Pr) in shellfish bodies to determine whether the Nd in shellfish tissue was derived from solution in seawater or from suspended particulates. The εNd values in shellfish tissue varied regionally (−6 to +1), matching the ambient seawater, whereas all 87Sr/86Sr values were homogeneous and typical of seawater (0.7091–0.7092). The seawater εNd values were in turn correlated with those in the adjacent rivers, linking shellfish εNd to the geology of river catchments. The depletion of Ce compared to La and Pr (negative Ce anomaly) suggested that the Nd in shellfish was derived from the dissolved phase in seawater. Our results indicate that the distinct Nd isotope ratio derived from local geology is imprinted, through seawater, on the soft tissues of shellfish. This result underscores the potential of εNd as a tracer of coastal marine animals

マイクロハ ディジタル ヘンフクチョウ ホウシキ ニオケル タイイキナイ シンプク ヘンサ ト ビット アヤマリリツ ノ カンケイ

The bit error rates for some microwave digital modulation systems with additive white Gaussian noise and intersymbol interference caused by the effect of frequency selective fading are theoretically evaluated. The results reveal that there is direct proportional relation between in-band amplitude dispersion and bit error rate, as it was suggested in some experiments. Also the in-band amplitude dispersion for bit error rate of 10^ versus number of levels of multilevel modulation systems is presented

Antibody titers against SARS-CoV-2 decline, but do not disappear for several months

Background: To develop an effective vaccine against a novel viral pathogen, it is important to understand the longitudinal antibody responses against its first infection. Here we performed a longitudinal study of antibody responses against SARS-CoV-2 in symptomatic patients. Methods: Sequential blood samples were collected from 39 individuals at various timepoints between 0 and 154 days after onset. IgG or IgM titers to the receptor binding domain (RBD) of the S protein, the ectodomain of the S protein, and the N protein were determined by using an ELISA. Neutralizing antibody titers were measured by using a plaque reduction assay. Findings: The IgG titers to the RBD of the S protein, the ectodomain of the S protein, and the N protein peaked at about 20 days after onset, gradually decreased thereafter, and were maintained for several months after onset. Extrapolation modeling analysis suggested that the IgG antibodies were maintained for this amount of time because the rate of reduction slowed after 30 days post-onset. IgM titers to the RBD decreased rapidly and disappeared in some individuals after 90 days post-onset. All patients, except one, possessed neutralizing antibodies against authentic SARS-CoV-2, which they retained at 90 days after onset. The highest antibody titers in patients with severe infections were higher than those in patients with mild or moderate infections, but the decrease in antibody titer in the severe infection cohort was more remarkable than that in the mild or moderate infection cohort. Interpretation: Although the number of patients is limited, our results show that the antibody response against the first SARS-CoV-2 infection in symptomatic patients is typical of that observed in an acute viral infection

Differences among epitopes recognized by neutralizing antibodies induced by SARS-CoV-2 infection or COVID-19 vaccination

SARS-CoV-2 has gradually acquired amino acid substitutions in its S protein that reduce the potency of neutralizing antibodies, leading to decreased vaccine efficacy. Here, we attempted to obtain mutant viruses by passaging SARS-CoV-2 in the presence of plasma samples from convalescent patients or vaccinees to determine which amino acid substitutions affect the antigenicity of SARS-CoV-2. Several amino acid substitutions in the S2 region, as well as the N-terminal domain (NTD) and receptor-binding domain (RBD), affected the neutralization potency of plasma samples collected from vaccinees, indicating that amino acid substitutions in the S2 region as well as those in the NTD and RBD affect neutralization by vaccine-induced antibodies. Furthermore, the neutralizing potency of vaccinee plasma samples against mutant viruses we obtained or circulating viruses differed among individuals. These findings suggest that genetic backgrounds of vaccinees influence the recognition of neutralizing epitopes

Two new phenolic glucosides and an ellagitannin from the leaves of Castanopsis sclerophylla

In the course of a chemotaxonomical study of Castanopsis species (Fagaceae), detailed investigation of the leaves of C. sclerophylla led to isolation of three new phenolic compounds together with 62 known compounds. The structures of the new compounds were elucidated as 2-O-galloyl-O-4,6-(S)-valoneoyl-d-glucose (1), 6-O-galloyl-1-O-vanilloyl-β-d-glucose (2), and 4″-O-galloylchestanin (3) by means of spectroscopic analyses and enzymatic hydrolysis with tannase. Comparison with other Castanopsis species indicated that C. sclerophylla characteristically accumulates chlorogenic acid and a dimeric ellagitannin, rugosin E. Triterpene hexahydroxydiphenoyl esters, which are major constituents of C. cuspidata var. sieboldii, C. hystrix, and C. fissa were not detected

Dysregulation of RNF213 promotes cerebral hypoperfusion

RNF213 is a susceptibility gene for moyamoya disease, yet its exact functions remain unclear. To evaluate the role of RNF213 in adaptation of cerebral blood flow (CBF) under cerebral hypoperfusion, we performed bilateral common carotid artery stenosis surgery using external microcoils on Rnf213 knockout (KO) and vascular endothelial cell-specific Rnf213 mutant (human p.R4810K orthologue) transgenic (EC-Tg) mice. Temporal CBF changes were measured by arterial spin-labelling magnetic resonance imaging. In the cortical area, no significant difference in CBF was found before surgery between the genotypes. Three of eight (37.5%) KO mice died after surgery but all wild-type and EC-Tg mice survived hypoperfusion. KO mice had a significantly more severe reduction in CBF on day 7 than wild-type mice (KO, 29.7% of baseline level; wild-type, 49.3%; p = 0.038), while CBF restoration on day 28 was significantly impaired in both KO (50.0%) and EC-Tg (56.1%) mice compared with wild-type mice (69.5%; p = 0.031 and 0.037, respectively). Changes in the subcortical area also showed the same tendency as the cortical area. Additionally, histological analysis demonstrated that angiogenesis was impaired in both EC-Tg and KO mice. These results are indicative of the essential role of RNF213 in the maintenance of CBF

Triterpene hexahydroxydiphenoyl esters and a quinic acid purpurogallin carbonyl ester from the leaves of Castanopsis fissa.

Triterpene hexahydroxydiphenoyl (HHDP) esters have only been isolated from Castanopsis species, and the distribution of these esters in nature is of chemotaxonomical interest. In this study, the chemical constituents of the leaves of Castanopsis fissa were examined in detail to identify and isolate potential HHDP esters. Together with 53 known compounds, 3,4-di-O-galloyl-1-O-purpurogallin carbonyl quinic acid (1) and 3,24-(S)-HHDP-2α,3β,23,24-tetrahydroxytaraxastan-28,20β-olide (2) were isolated and their structures were elucidated by spectroscopic and chemical methods. The polyphenols of the leaves were mainly composed of galloyl quinic acids, triterpenes HHDP esters, ellagitannins and flavonol glycosides. In particular, the isolation yields of 1,3,4-trigalloyl quinic acid and compound 2 were 1.53% and 0.27%, respectively, from the fresh leaves. The presence of lipid soluble HHDP esters of oleanane-type triterpenes as one of the major metabolites is an important chemotaxonomical discovery. Lipase inhibition activities and ORAC values of the major constituents were compared. The triterpene HHDP ester showed moderate lipase inhibition activity and myricitrin gave the largest ORAC value

Tumor Marker Levels Before and After Curative Treatment of Hepatocellular Carcinoma as Predictors of Patient Survival.

BACKGROUND: α-fetoprotein (AFP) is used as a marker for hepatocellular carcinoma (HCC), which is influenced by hepatitis. Protein-induced vitamin K absence or antagonist II (PIVKA-II) is a sensitive diagnostic marker. Changes in these markers after treatment may reflect curability and predict outcome. METHODS: We conducted an analysis of prognosis in 470 HCC patients who received curative treatments, and examined the relationship between changes in AFP and PIVKA-II levels after 1 month of treatment in 156 patients. Subjects were divided into three groups according to changes in both levels: (1) normal (L) group before treatment, (2) normalization (N) or (3) decreased but still above normal level or unchanged (ANU) group after treatment. RESULTS: High AFP and PIVKA-II levels were significantly associated with poor tumor-free and overall survival. The presence of large size and advanced stage were significantly associated with prevalence of DU group. Overall survival in the AFP-L group was significantly better than that of other groups and overall survival in PIVKA-II-L and N groups were significantly better than that of the PIVKA-II-ANU groups. The combination of changes in the AFP- ANU and PIVKA-II- ANU groups showed the worst tumor-free and overall survivals. Multivariate analysis identified high pre-treatment levels of AFP and PIVKA-II and combination of AFP- ANU and PIVKA-II- ANU as significant determinants of poor tumor-free and overall survival, particularly in patients who underwent hepatectomy. CONCLUSION: We conclude that high levels of AFP or PIVKA-II after treatment for HCC did not sufficiently reflect curative efficacy of treatment and reflected a poor predictor of prognosis in HCC patients